"Gunwalking" scandal final straw leading to resignation of U.S. ambassador to Mexico

Newly appointed US ambassador to Mexico, Carlos Pascual, speaks during his first press conference at the International Airport in Mexico City, on 11 August, 2009. AFP PHOTO/Alfredo Estrella (Photo credit should read ALFREDO ESTRELLA/AFP/Getty Images)

ALFREDO ESTRELLA/AFP/Getty Images

Newly appointed US ambassador to Mexico, Carlos Pascual, speaks during his first press conference at the International Airport in Mexico City, on 11 August, 2009. AFP PHOTO/Alfredo Estrella (Photo credit should read ALFREDO ESTRELLA/AFP/Getty Images)
ALFREDO ESTRELLA/AFP/Getty Images

The U.S. ambassador to Mexico, Carlos Pascual, has resigned under pressure.

In recent weeks, Mexico's President Felipe Calderon has said in public he doesn't trust Pascual (seen at left). Several sources close to diplomatic circles inside Mexico tell CBS News that from Mexico's viewpoint, the ATF "gunwalking" scandal was the final straw in a series of controversies.

First, Pascual has been dating the daughter of a mistrusted and alleged cartel-linked opposition legislator.

Second, Pascual's critical views of Mexico in secret U.S. diplomatic cables were leaked on WikiLeaks several weeks ago. In one cable, Pascual said Mexico had turned a blind eye to U.S. leads on how to capture drug lords.

More recently, Mexico has demanded information from the U.S. on the ATF controversy revealed by CBS News, in which ATF agents allegedly allowed thousands of weapons to cross the border, supposedly in a failed attempt to gain intelligence to take down a major drug cartel. Some Mexican legislators have publicly said ATF agents who crafted and carried out the strategy could be extradited to Mexico and arrested. The legislators quote ATF agent John Dodson, as interviewed in our report.

Published reports, including one in the Miami Herald, quote the White House as recently having said U.S. officials thought the tiffs would blow over.